Leptin is produced as a 167-aa residue preprohormone,
including an N-terminal 21-aa signal peptide,
and is released as a 146-aa peptide after enzymatic
cleavage.
Human leptin: Mr 16,000, pI 5.8. Leptin is soluble in
water.
Leptin analogs are used for the treatment of lipodystrophy
in clinical settings.
Gene, mRNA, and precursor
The human leptin gene, LEP, location 7q31.3, consists
of three exons. Human leptin mRNA has a 3.5kb length
that encodes a signal peptide of 21 aa residues and a
mature protein of 146 aa residues.
Regulation of synthesis and release
The synthesis and release of leptin are regulated by
environmental factors. In humans and rodents, obesity
stimulates leptin synthesis and increases the plasma
concentrations. Exercise decreases the plasma leptin concentrations
in the rat. Exposure to low temperature suppresses
leptin gene expression in WAT and reduces the
plasma leptin concentrations in rodents. While fasting
attenuates leptin gene expression, feeding restores the
levels of gene expression.
Leptin is an adipocyte hormone secreted from white adipose
tissues that regulates energy expenditure and food intake
by acting on receptors located in the hypothalamus.
